1. Field of the Invention
This invention relates to integrated circuits and, more particularly, to the decapping of packaged integrated circuits to allow analysis and testing.
2. Description of the Relevant Art
When the fabrication process of a semiconductor chip is completed, the semiconductor is still vulnerable to contamination and devoid of electrical connections. The semiconductor chip must therefore be mounted within a package and connected to the outside world via package connections. Typical packages include plastic dual in-line packages (PDIP), plastic lead chip carrier (PLCC) packages and glass-sealed cerquad packages.
After a semiconductor chip has been packaged, it is frequently desirable to test and analyze the packaged integrated circuit. If access to the semiconductor chip is required, a portion of the package must be cut or broken to expose the chip. To illustrate this, FIG. 1 is a perspective view of a glass-sealed cerquad packaged integrated circuit 5. The cerquad package includes a main body section 10 having a lower base portion 12 and an upper cap portion 14. The base portion 12 and the cap portion 14 are composed of a hard ceramic material and are sandwiched together such that a semiconductor chip is housed and protected within. A layer of glass forming a glass interface layer 16 is deposited between and bonds the base portion 12 and the cap portion 14. A plurality of wire leads 18 extend from within the main body section 10 to a plastic ring section 19. The plastic ring section 19 is provided to maintain the integrity and uniformity of the wire leads 18.
One approach to exposing the semiconductor chip is to use hand held chisels to crack the glass interface layer 16 and pry the cap portion 14 from the base portion 12. Since access to the glass interface layer 16 is restricted due to the plastic ring section 19, it is difficult to apply a uniform cracking force to decap the main body section 10. Therefore, this approach frequently causes undesirable breakage of the base portion 12 and the cap portion 14 and causes non-uniform breakage of the glass interface layer 16. In addition, the wire leads 18 extending within and from the main body 10 are frequently broken or bent. Finally, minute glass fragments and other debris resulting from the breakage can contact and damage the semiconductor chip, rendering subsequent testing procedures useless.